I am trying to apply MOHID3D to a nearshore zone with somewhat complicated coastlines and islets, but it crashes over and over.Here is the description of my simulation:

-I used the same modules as in the Tagus sample only without discharge module.

-My bathymetry was made by MOHID Studio using the option of constant spaced grid, (DX, DY = 0.005 dgree).

-Tide was generated as fes2004.nc

When I tried a time increment DT=10sec (Courant Number is 1.015), the model ran very well.But when DT was bigger than 10sec (Courant Number exists between 3 and 4), the model execution after several time steps stopped showing a log message like

T,S,i,j,k -9.8999995E+15 -9.8999995E+15 227 342 2

Then I turned off the keyword ADVECTION_DIFFUSION (other options are the same), and found that the model ran well (even with DT=30).

Can anybody tell me how to get a complete run even with (DT =30, ADVECTION_DIFFUSION : 1)?